/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2002-2005 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: XPathResultImpl.java,v 1.2.4.1 2005/09/10 04:18:54 jeffsuttor Exp $
 */

package com.sun.org.apache.xpath.internal.domapi;

import javax.xml.transform.TransformerException;

import com.sun.org.apache.xpath.internal.XPath;
import com.sun.org.apache.xpath.internal.objects.XObject;
import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;
import com.sun.org.apache.xpath.internal.res.XPATHMessages;
import org.w3c.dom.DOMException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.events.Event;
import org.w3c.dom.events.EventListener;
import org.w3c.dom.events.EventTarget;
import org.w3c.dom.traversal.NodeIterator;
import org.w3c.dom.xpath.XPathException;
import org.w3c.dom.xpath.XPathResult;

/**
 *
 * The class provides an implementation XPathResult according
 * to the DOM L3 XPath Specification, Working Group Note 26 February 2004.
 *
 * <p>See also the <a href='http://www.w3.org/TR/2004/NOTE-DOM-Level-3-XPath-20040226'>Document Object Model (DOM) Level 3 XPath Specification</a>.</p>
 *
 * <p>The <code>XPathResult</code> interface represents the result of the
 * evaluation of an XPath expression within the context of a particular
 * node. Since evaluation of an XPath expression can result in various
 * result types, this object makes it possible to discover and manipulate
 * the type and value of the result.</p>
 *
 * <p>This implementation wraps an <code>XObject</code>.
 *
 * @see com.sun.org.apache.xpath.internal.objects.XObject
 * @see org.w3c.dom.xpath.XPathResult
 *
 * @xsl.usage internal
 */
class XPathResultImpl implements XPathResult, EventListener {

    /**
    *  The wrapped XObject
    */
    final private XObject m_resultObj;

    /**
     * The xpath object that wraps the expression used for this result.
     */
    final private XPath m_xpath;

    /**
    *  This the type specified by the user during construction.  Typically
     *  the constructor will be called by com.sun.org.apache.xpath.internal.XPath.evaluate().
    */
    final private short m_resultType;

    private boolean m_isInvalidIteratorState = false;

    /**
     * Only used to attach a mutation event handler when specified
     * type is an iterator type.
     */
    final private Node m_contextNode;

    /**
    *  The iterator, if this is an iterator type.
    */
    private NodeIterator m_iterator = null;;

    /**
    *  The list, if this is a snapshot type.
    */
    private NodeList m_list = null;

    /**
     * Constructor for XPathResultImpl.
    *
    * For internal use only.
     */
    XPathResultImpl(short type, XObject result, Node contextNode, XPath xpath) {
        // Check that the type is valid
        if (!isValidType(type)) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INVALID_XPATH_TYPE, new Object[] { new Integer(type) });
            throw new XPathException(XPathException.TYPE_ERR, fmsg); // Invalid XPath type argument: {0}
        }

        // Result object should never be null!
        if (null == result) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_EMPTY_XPATH_RESULT, null);
            throw new XPathException(XPathException.INVALID_EXPRESSION_ERR, fmsg); // Empty XPath result object
        }

        this.m_resultObj = result;
        this.m_contextNode = contextNode;
        this.m_xpath = xpath;

        // If specified result was ANY_TYPE, determine XObject type
        if (type == ANY_TYPE) {
            this.m_resultType = getTypeFromXObject(result);
        } else {
            this.m_resultType = type;
        }

        // If the context node supports DOM Events and the type is one of the iterator
        // types register this result as an event listener
        if (((m_resultType == XPathResult.ORDERED_NODE_ITERATOR_TYPE) || (m_resultType == XPathResult.UNORDERED_NODE_ITERATOR_TYPE))) {
            addEventListener();

        } // else can we handle iterator types if contextNode doesn't support EventTarget??

        // If this is an iterator type get the iterator
        if ((m_resultType == ORDERED_NODE_ITERATOR_TYPE) || (m_resultType == UNORDERED_NODE_ITERATOR_TYPE) || (m_resultType == ANY_UNORDERED_NODE_TYPE) || (m_resultType == FIRST_ORDERED_NODE_TYPE)) {

            try {
                m_iterator = m_resultObj.nodeset();
            } catch (TransformerException te) {
                // probably not a node type
                String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INCOMPATIBLE_TYPES, new Object[] { m_xpath.getPatternString(), getTypeString(getTypeFromXObject(m_resultObj)), getTypeString(m_resultType) });
                throw new XPathException(XPathException.TYPE_ERR, fmsg); // "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be coerced into the specified XPathResultType of {2}."},
            }

            // If user requested ordered nodeset and result is unordered
            // need to sort...TODO
            //            if ((m_resultType == ORDERED_NODE_ITERATOR_TYPE) &&
            //                (!(((DTMNodeIterator)m_iterator).getDTMIterator().isDocOrdered()))) {
            //
            //            }

            // If it's a snapshot type, get the nodelist
        } else if ((m_resultType == UNORDERED_NODE_SNAPSHOT_TYPE) || (m_resultType == ORDERED_NODE_SNAPSHOT_TYPE)) {
            try {
                m_list = m_resultObj.nodelist();
            } catch (TransformerException te) {
                // probably not a node type
                String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INCOMPATIBLE_TYPES, new Object[] { m_xpath.getPatternString(), getTypeString(getTypeFromXObject(m_resultObj)), getTypeString(m_resultType) });
                throw new XPathException(XPathException.TYPE_ERR, fmsg); // "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be coerced into the specified XPathResultType of {2}."},
            }
        }
    }

    /**
     * @see org.w3c.dom.xpath.XPathResult#getResultType()
     */
    public short getResultType() {
        return m_resultType;
    }

    /**
     *  The value of this number result.
    * @exception XPathException
    *   TYPE_ERR: raised if <code>resultType</code> is not
    *   <code>NUMBER_TYPE</code>.
     * @see org.w3c.dom.xpath.XPathResult#getNumberValue()
     */
    public double getNumberValue() throws XPathException {
        if (getResultType() != NUMBER_TYPE) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_XPATHRESULTTYPE_TO_NUMBER, new Object[] { m_xpath.getPatternString(), getTypeString(m_resultType) });
            throw new XPathException(XPathException.TYPE_ERR, fmsg);
            //              "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a number"
        } else {
            try {
                return m_resultObj.num();
            } catch (Exception e) {
                // Type check above should prevent this exception from occurring.
                throw new XPathException(XPathException.TYPE_ERR, e.getMessage());
            }
        }
    }

    /**
     * The value of this string result.
    * @exception XPathException
    *   TYPE_ERR: raised if <code>resultType</code> is not
    *   <code>STRING_TYPE</code>.
    *
     * @see org.w3c.dom.xpath.XPathResult#getStringValue()
     */
    public String getStringValue() throws XPathException {
        if (getResultType() != STRING_TYPE) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_TO_STRING, new Object[] { m_xpath.getPatternString(), m_resultObj.getTypeString() });
            throw new XPathException(XPathException.TYPE_ERR, fmsg);
            //              "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a string."
        } else {
            try {
                return m_resultObj.str();
            } catch (Exception e) {
                // Type check above should prevent this exception from occurring.
                throw new XPathException(XPathException.TYPE_ERR, e.getMessage());
            }
        }
    }

    /**
     * @see org.w3c.dom.xpath.XPathResult#getBooleanValue()
     */
    public boolean getBooleanValue() throws XPathException {
        if (getResultType() != BOOLEAN_TYPE) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_TO_BOOLEAN, new Object[] { m_xpath.getPatternString(), getTypeString(m_resultType) });
            throw new XPathException(XPathException.TYPE_ERR, fmsg);
            //              "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a boolean."
        } else {
            try {
                return m_resultObj.bool();
            } catch (TransformerException e) {
                // Type check above should prevent this exception from occurring.
                throw new XPathException(XPathException.TYPE_ERR, e.getMessage());
            }
        }
    }

    /**
     * The value of this single node result, which may be <code>null</code>.
    * @exception XPathException
    *   TYPE_ERR: raised if <code>resultType</code> is not
    *   <code>ANY_UNORDERED_NODE_TYPE</code> or
    *   <code>FIRST_ORDERED_NODE_TYPE</code>.
    *
     * @see org.w3c.dom.xpath.XPathResult#getSingleNodeValue()
     */
    public Node getSingleNodeValue() throws XPathException {

        if ((m_resultType != ANY_UNORDERED_NODE_TYPE) && (m_resultType != FIRST_ORDERED_NODE_TYPE)) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_CONVERT_TO_SINGLENODE, new Object[] { m_xpath.getPatternString(), getTypeString(m_resultType) });
            throw new XPathException(XPathException.TYPE_ERR, fmsg);
            //                              "The XPathResult of XPath expression {0} has an XPathResultType of {1} which cannot be converted to a single node.
            //                               This method applies only to types ANY_UNORDERED_NODE_TYPE and FIRST_ORDERED_NODE_TYPE."
        }

        NodeIterator result = null;
        try {
            result = m_resultObj.nodeset();
        } catch (TransformerException te) {
            throw new XPathException(XPathException.TYPE_ERR, te.getMessage());
        }

        if (null == result)
            return null;

        Node node = result.nextNode();

        // Wrap "namespace node" in an XPathNamespace
        if (isNamespaceNode(node)) {
            return new XPathNamespaceImpl(node);
        } else {
            return node;
        }
    }

    /**
     * @see org.w3c.dom.xpath.XPathResult#getInvalidIteratorState()
     */
    public boolean getInvalidIteratorState() {
        return m_isInvalidIteratorState;
    }

    /**
     * The number of nodes in the result snapshot. Valid values for
    * snapshotItem indices are <code>0</code> to
    * <code>snapshotLength-1</code> inclusive.
    * @exception XPathException
    *   TYPE_ERR: raised if <code>resultType</code> is not
    *   <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or
    *   <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.
    *
     * @see org.w3c.dom.xpath.XPathResult#getSnapshotLength()
     */
    public int getSnapshotLength() throws XPathException {

        if ((m_resultType != UNORDERED_NODE_SNAPSHOT_TYPE) && (m_resultType != ORDERED_NODE_SNAPSHOT_TYPE)) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_CANT_GET_SNAPSHOT_LENGTH, new Object[] { m_xpath.getPatternString(), getTypeString(m_resultType) });
            throw new XPathException(XPathException.TYPE_ERR, fmsg);
            //                              "The method getSnapshotLength cannot be called on the XPathResult of XPath expression {0} because its XPathResultType is {1}.
        }

        return m_list.getLength();
    }

    /**
     * Iterates and returns the next node from the node set or
    * <code>null</code>if there are no more nodes.
    * @return Returns the next node.
    * @exception XPathException
    *   TYPE_ERR: raised if <code>resultType</code> is not
    *   <code>UNORDERED_NODE_ITERATOR_TYPE</code> or
    *   <code>ORDERED_NODE_ITERATOR_TYPE</code>.
    * @exception DOMException
    *   INVALID_STATE_ERR: The document has been mutated since the result was
    *   returned.
     * @see org.w3c.dom.xpath.XPathResult#iterateNext()
     */
    public Node iterateNext() throws XPathException, DOMException {
        if ((m_resultType != UNORDERED_NODE_ITERATOR_TYPE) && (m_resultType != ORDERED_NODE_ITERATOR_TYPE)) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_NON_ITERATOR_TYPE, new Object[] { m_xpath.getPatternString(), getTypeString(m_resultType) });
            throw new XPathException(XPathException.TYPE_ERR, fmsg);
            //                "The method iterateNext cannot be called on the XPathResult of XPath expression {0} because its XPathResultType is {1}.
            //                This method applies only to types UNORDERED_NODE_ITERATOR_TYPE and ORDERED_NODE_ITERATOR_TYPE."},
        }

        if (getInvalidIteratorState()) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_DOC_MUTATED, null);
            throw new DOMException(DOMException.INVALID_STATE_ERR, fmsg); // Document mutated since result was returned. Iterator is invalid.
        }

        Node node = m_iterator.nextNode();
        if (null == node)
            removeEventListener(); // JIRA 1673
        // Wrap "namespace node" in an XPathNamespace
        if (isNamespaceNode(node)) {
            return new XPathNamespaceImpl(node);
        } else {
            return node;
        }
    }

    /**
     * Returns the <code>index</code>th item in the snapshot collection. If
     * <code>index</code> is greater than or equal to the number of nodes in
     * the list, this method returns <code>null</code>. Unlike the iterator
     * result, the snapshot does not become invalid, but may not correspond
     * to the current document if it is mutated.
     * @param index Index into the snapshot collection.
     * @return The node at the <code>index</code>th position in the
     *   <code>NodeList</code>, or <code>null</code> if that is not a valid
     *   index.
     * @exception XPathException
     *   TYPE_ERR: raised if <code>resultType</code> is not
     *   <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or
     *   <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.
     *
         * @see org.w3c.dom.xpath.XPathResult#snapshotItem(int)
         */
    public Node snapshotItem(int index) throws XPathException {

        if ((m_resultType != UNORDERED_NODE_SNAPSHOT_TYPE) && (m_resultType != ORDERED_NODE_SNAPSHOT_TYPE)) {
            String fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_NON_SNAPSHOT_TYPE, new Object[] { m_xpath.getPatternString(), getTypeString(m_resultType) });
            throw new XPathException(XPathException.TYPE_ERR, fmsg);
            //              "The method snapshotItem cannot be called on the XPathResult of XPath expression {0} because its XPathResultType is {1}.
            //              This method applies only to types UNORDERED_NODE_SNAPSHOT_TYPE and ORDERED_NODE_SNAPSHOT_TYPE."},
        }

        Node node = m_list.item(index);

        // Wrap "namespace node" in an XPathNamespace
        if (isNamespaceNode(node)) {
            return new XPathNamespaceImpl(node);
        } else {
            return node;
        }
    }

    /**
     * Check if the specified type is one of the supported types.
     * @param type The specified type
     *
     * @return true If the specified type is supported; otherwise, returns false.
     */
    static boolean isValidType(short type) {
        switch (type) {
            case ANY_TYPE:
            case NUMBER_TYPE:
            case STRING_TYPE:
            case BOOLEAN_TYPE:
            case UNORDERED_NODE_ITERATOR_TYPE:
            case ORDERED_NODE_ITERATOR_TYPE:
            case UNORDERED_NODE_SNAPSHOT_TYPE:
            case ORDERED_NODE_SNAPSHOT_TYPE:
            case ANY_UNORDERED_NODE_TYPE:
            case FIRST_ORDERED_NODE_TYPE:
                return true;
            default:
                return false;
        }
    }

    /**
     * @see org.w3c.dom.events.EventListener#handleEvent(Event)
     */
    public void handleEvent(Event event) {

        if (event.getType().equals("DOMSubtreeModified")) {
            // invalidate the iterator
            m_isInvalidIteratorState = true;

            // deregister as a listener to reduce computational load
            removeEventListener();
        }
    }

    /**
     * Given a request type, return the equivalent string.
     * For diagnostic purposes.
     *
     * @return type string
     */
    private String getTypeString(int type) {
        switch (type) {
            case ANY_TYPE:
                return "ANY_TYPE";
            case ANY_UNORDERED_NODE_TYPE:
                return "ANY_UNORDERED_NODE_TYPE";
            case BOOLEAN_TYPE:
                return "BOOLEAN";
            case FIRST_ORDERED_NODE_TYPE:
                return "FIRST_ORDERED_NODE_TYPE";
            case NUMBER_TYPE:
                return "NUMBER_TYPE";
            case ORDERED_NODE_ITERATOR_TYPE:
                return "ORDERED_NODE_ITERATOR_TYPE";
            case ORDERED_NODE_SNAPSHOT_TYPE:
                return "ORDERED_NODE_SNAPSHOT_TYPE";
            case STRING_TYPE:
                return "STRING_TYPE";
            case UNORDERED_NODE_ITERATOR_TYPE:
                return "UNORDERED_NODE_ITERATOR_TYPE";
            case UNORDERED_NODE_SNAPSHOT_TYPE:
                return "UNORDERED_NODE_SNAPSHOT_TYPE";
            default:
                return "#UNKNOWN";
        }
    }

    /**
     * Given an XObject, determine the corresponding DOM XPath type
     *
     * @return type string
     */
    private short getTypeFromXObject(XObject object) {
        switch (object.getType()) {
            case XObject.CLASS_BOOLEAN:
                return BOOLEAN_TYPE;
            case XObject.CLASS_NODESET:
                return UNORDERED_NODE_ITERATOR_TYPE;
            case XObject.CLASS_NUMBER:
                return NUMBER_TYPE;
            case XObject.CLASS_STRING:
                return STRING_TYPE;
            // XPath 2.0 types
            //          case XObject.CLASS_DATE:
            //          case XObject.CLASS_DATETIME:
            //          case XObject.CLASS_DTDURATION:
            //          case XObject.CLASS_GDAY:
            //          case XObject.CLASS_GMONTH:
            //          case XObject.CLASS_GMONTHDAY:
            //          case XObject.CLASS_GYEAR:
            //          case XObject.CLASS_GYEARMONTH:
            //          case XObject.CLASS_TIME:
            //          case XObject.CLASS_YMDURATION: return STRING_TYPE; // treat all date types as strings?

            case XObject.CLASS_RTREEFRAG:
                return UNORDERED_NODE_ITERATOR_TYPE;
            case XObject.CLASS_NULL:
                return ANY_TYPE; // throw exception ?
            default:
                return ANY_TYPE; // throw exception ?
        }

    }

    /**
     * Given a node, determine if it is a namespace node.
     *
     * @param node
     *
     * @return boolean Returns true if this is a namespace node; otherwise, returns false.
     */
    private boolean isNamespaceNode(Node node) {

        if ((null != node) && (node.getNodeType() == Node.ATTRIBUTE_NODE) && (node.getNodeName().startsWith("xmlns:") || node.getNodeName().equals("xmlns"))) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Add m_contextNode to Event Listner to listen for Mutations Events
     *
     */
    private void addEventListener() {
        if (m_contextNode instanceof EventTarget)
            ((EventTarget) m_contextNode).addEventListener("DOMSubtreeModified", this, true);

    }

    /**
     * Remove m_contextNode to Event Listner to listen for Mutations Events
     *
     */
    private void removeEventListener() {
        if (m_contextNode instanceof EventTarget)
            ((EventTarget) m_contextNode).removeEventListener("DOMSubtreeModified", this, true);
    }

}
